radio merit badge—part 2

Radio Merit Badge—Part 2 Radio Merit Badge—Part 2

November 19, 2005

Presented by

John Chamberlain AC5CV

A Radio StationA Radio Station

TransmitterCreates radio waves at a desired frequency (tuning).Adds information to those waves.For example, takes information (a microphone) from a voice and adds that to the radio waves (“modulation”).

ReceiverReceives radio signals of all frequencies.Amplifies the radio waves of a desired frequency (tuning).Converts the information in the waves to audio frequencies: output through a speaker.

Transceiver: Transmitter and Receiver in one unit.

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A Radio StationA Radio Station

AmplifierGreatly increases the voltage (the strength) of the electric waves coming out of the transmitter.

This generally helps your signal reach farther (up to a point).

AntennaWhen transmitting: acts like a megaphone, lets the electric waves spread out in the desired direction.

When receiving: acts like a “big ear” that collects the electric wave energy.

To be most efficient, antennas must be “tuned” to the radio frequency, just like the the transmitter and receiver are tuned.

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Antennas: The DipoleAntennas: The DipoleSize of the antenna is based on the frequency, or the wavelength.

Transceiver146 MHz

38.5 in.

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Length (in ft) = 468/f where f=freq in MHz

Example: for f = 146 MHz Length = 468/146 = 3.2 ft,

or 38.5 inches

Total dipole length equals half the “wavelength”

Antennas: “Whips”Antennas: “Whips”

Vertical whips are often attached to a magnet.

Often called “a “mag-mount.”

Typically, they are ¼ wavelength, but can also be 58 wavelength.

Magmounts require a metal surface—both physically, and electrically.

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Antennas: “Beams”Antennas: “Beams”

Parallel “dipoles” strengthen the signal in one direction.

They “beam” the radio signal in one main direction.

Also receive the signals from that same direction.

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Antennas of all shapes!Antennas of all shapes!12-13

Safety First!Safety First!

Working on radios can be dangerous!They use electricity: often very high voltages!

Radio waves themselves can cause burns!

So, don’t touch an antenna when someone is transmitting!

PLEASE: DON’T DO ANY WORK ON ELECTRONIC EQUIPMENT YOURSELF until you have learned from an experienced worker.

And, did you know? It is illegal to work on radio transmitters without a license!


Electrical shock can hurt or kill you!Make sure the power is disconnected before working.

Even with the power off, some parts inside the radio can hold a dangerous electrical charge.

If you aren’t sure what you are doing: GET HELP!


Radio Frequency (RF) energy can burn you badly. Keep antennas out of reach of people and animals. RF radiation can be unhealthy. Don’t use a radio when it is not completely assembled. The case keeps the RF radiation contained.Make sure the antennas can’t touch any power lines, or you could be electrocuted when using the radio.


Lightning can hit your antenna and travel down your lines to the radio. Make sure your antenna and radio are grounded to a good “earth ground.” Be very careful working on towers and roofs.

A fall will surely hurt you, and might even KILL you! Falling tools or other objects can hurt people below.

Block Diagram vs. Block Diagram vs. Schematic DiagramSchematic Diagram

Block diagramShows parts of radio station.

Schematic diagram Shows how the electrical circuit works.

It uses schematic symbols to show the path of a circuit—similar to the way a map uses “map symbols” to show the path of travel on a hiking trail.

Block Diagram of RadioBlock Diagram of Radio

Mic Transceiver Amp

PowerSupply

AntTuner Feedline

Ant

CircuitsCircuits

An electrical circuit is made up of wires and various electrical components

Together they make up the electronic part of your electrical appliance, in this case: a radio.

Kinds of CircuitsKinds of Circuits

Open circuit: No current. No electrical contact. For example, when a light switch is “off.”Closed circuit: Electricity flows correctly along the proper path. For example, when a light switch is “on.”Short circuit: Electricity flows incorrectly, from the source to the other side of the circuit, usually causing serious damage. For example, a frayed lamp cord, where the wire insulation is worn so the two wires can touch each other. Pow! Very dangerous!

Schematic SymbolsSchematic Symbols

A picture that represents an electronic part in a circuit.

Let’s learn some of the more common symbols.

You will have to identify three actual parts for this merit badge.


Fuse Battery

Resistor Variable Resistor


Earth Ground Inductor (coil)

Capacitor Variable Capacitor


B

E

C

DiodeLight-Emitting Diode

Transistor (NPN) Op-Amp


Transformer Antenna

Speaker Switch

What Can Amateur Radio What Can Amateur Radio Operators Do on the Air?Operators Do on the Air?

Jamboree On The Air (JOTA) is the third weekend every October when Scouts all over the world talk to each other on ham radio.DX! Lots of hams like to talk to other hams around the world and collect postcards called QSL cards to prove they did it. It’s a great way to have fun and learn about geography.


Contests are held many weekends. For example, you try to contact as many people from a certain place or in a certain way.

Service at parades & special events. Ham radio operators are often the best people to help with communication at community events, from small carnivals to large parades and “runs.”


Disasters: Hams are often called to help during fires, floods, earthquakes, and other disasters. At these times, telephone and cellular phone systems are often damaged or overloaded, and ham radio is the only reliable communication. Skywarn: Amateur radio operators help the National Weather Service by reporting severe weather conditions.


Digital Communications: Hams can connect their computers to their radios. Then they can send electronic messages and pictures–wireless e-mail!

Portable Radio Operations: Amateur radio is great fun when done away from home! On a campout, using solar power and a wire antenna suspended by trees: imagine chatting with someone in another country, or just letting the folks back home know how things are going.

Q SignalsQ Signals

Q-signals are short, three letter codes mainly used in a Morse code QSO—that is, a Morse code radio contact.Sometimes, we also use these codes for voice communication. But in a “phone” QSO, it’s usually better to just say what you mean.

“I live in Waco, Texas”Not “My QTH is Waco, Texas”

Q Signals Q Signals (used with Morse code)(used with Morse code)

QTH: Your locationExample: My QTH is Waco, TX.

QRM: Man-made interference Example: I am experiencing QRM.

QRN: Static interferenceExample: I am experiencing QRM.

QRP: Low power (5 watts or less)Example: I am transmitting QRP.

Q Signals Q Signals (used with Morse code)(used with Morse code)

QSB: Signal fadingExample: I am experiencing QSB.

QSL: Confirmation of contact informationExample: QSL on the brand of your radio there.

QSO: A radio contactExample: I had a QSO with Japan today.

QSY: Change of frequencyExample: Let’s QSY to 7010.

Technician ClassTechnician ClassThe Technician Class license is the entry level license: the “Tenderfoot” of ham radio. Simply pass a 35-question multiple choice test covering radio basics, rules, and procedures.No longer required to learn Morse code.Full privileges on the VHF bands, so you can use repeaters and hand-held radios around town.Not allowed to use the HF bands (except a little of the 10m band).Surprise! All the questions and answers are available for study (in books and on the Internet).Tests are given by other licensed amateurs who are called “volunteer examiners,” or “VEs.”

Emergency CallsEmergency Calls

Speak clearly and give complete information, just like when you make a 911 telephone call.

Remember to give your complete location, because the person on the radio may be in another state–or even another country!

“MAYDAY” is the international word for requesting help by radio. However, it is probably easier and less confusing to just say “EMERGENCY.”

Emergency CallsEmergency Calls

If no one hears you: might have to get higher–up a hill or tall building, for example.If using Morse code, send SOS

S O Suntil you make contact. Then send your information.Give your info slow enough for the other person to understand and write it down.

FCC and the Amateur Radio Service FCC and the Amateur Radio Service It’s a PRIVILEGE to use radios! So, in return…Service: Amateur operators (hams) are volunteers, serving the community—just like the Scouts. Experimentation: Hams are allowed to build their own radio equipment.Communication skills: Hams practice, and learn how to listen and talk on the radio.Self-training: Ham’s learn by doing, and by asking for help, and by helping each other.International goodwill: Because signals can travel worldwide, you can represent America.

Small and Big RadiosSmall and Big RadiosHandheld radios (HT): Small, light, portable, but not much power (3 watts). Some can fit in your pocket. With repeaters they can be quite useful. Great for hikes and bike rides.Mobile radios: Operate on 12 volts from car. More power (50 watts). Requires outside antenna.Base radios: Operate on 12 volts from home power supply. Lots of power (100 watts or more). Easier to use, with many nice features. Repeaters: Located high up (mountains, tall buildings, towers). Relay signals with high power and big antennas.

Choosing Your RadioChoosing Your RadioCost

Small, low-power radios cost less ($100-$200). Larger radios with more features cost more. Used radios cost less at “hamfests” (as little as $50)

Power Low-power radios work well for short distances or with repeaters, and can operate with batteries. High-powered radios can talk longer distances, but require more electricity.

Intended PurposeSmall radios are ideal for backpacking and camping. Medium-power radios work well in cars and trucks. High-powered radios are good for home “base” stations.

Requirement 7, Option A:Requirement 7, Option A:Simulated Radio ContactSimulated Radio Contact

Give and Receive (and log it)! Use Q-signals where indicated.

Call any station: CQ CQ CQ, This is <your station ID>.Station IDs (give yours, record theirs).Use your initials and age, for example: JDC12

Q Your location (city, state)Q Tell the other station that you “copied correctly”

Type of radio you are using (brand, etc.)Q You are transmitting with low powerQ Coordinate a change to another frequencyQ Are you having any difficulties, like static or interference?

Yes, let’s pretend (pick one).Q Thank the other station for “the contact”

Sign off, giving the other station ID and your station ID.

radio merit badge—part 2

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